1. Becoming a balanced, proficient bilingual: Predictions from age of acquisition & genetic background
Kelly A. Vaughn & Arturo E. Hernandez
University of Houston
Introduction
Results
Results
Genetic variants related to dopamine functioning (e.g., the ANKK1/TaqIa polymorphism from the DRD2 gene and the Val158Met polymorphism from the COMT gene) have previously been shown to predict cognitive flexibility and learning 1,2,3
These genetic variants may also predict second language learning 4, although this relationship may change across the lifespan 5
ANOVAs showed no significant differences based on DRD2 or COMT genotype or their interaction for:
Bilingual proficiency (F(5,111) = 0.15, p = 0.98)
AoA (F(5,111) = 0.94, p = 0.46)
SES (F(5,111) = 0.15, p = 0.98)
Genotype Combination n
Bilingual Proficiency
AoA
SES
Val/Val A1- 12
(6.12)
7.67 (2.96)
3.46 (1.41)
Val/Val A1+ 26
(7.50)
6.12 (1.68)
3.19 (1.40)
Val/Met A1- 19
(8.85)
7.11 (3.89)
3.16 (1.38)
Val/Met A1+ 41
(10.90)
6.05 (3.29)
3.37 (1.45)
Met/Met A1- 6
(14.91)
7.83 (5.31)
3.58 (1.36)
Met/Met A1+ 13
(13.64)
6.46 (2.44)
3.31 (1.76)
Garcia-Garcia et al. (2011)
Sugiura et al. (2011)
Multiple regression was used to predict bilingual proficiency from AoA, SES, and both DRD2 and COMT genotype: R2 = 0.28, Adjusted R2 = 0.20
Research Question:
Do ANKK1/TaqIa and Val158Met polymorphisms along with age of second language acquisition (AoA) predict levels of bilingual proficiency in Spanish-English bilinguals?
Hypothesis:
Genotypes associated with cognitive flexibility (Val/Val and A1+) would predict the highest bilingual proficiency, though this relationship may change when the second language is learned earlier in life
High bilingual proficiency was expected from groups with “balanced” levels of cortical and subcortical dopamine B SE β
Intercept (Met/Met A1+)
160.10
7.69
0.00***
A1-
-20.75
10.31
-0.95*
Val/Met
-19.74
8.06
-0.97*
Val/Val
3.09
10.17
0.14
AoA
-2.22
1.09
-0.68*
SES
0.40
0.61
0.06
Val/Met A1-
32.88
11.66
1.19*
Val/Val A1-
-6.14
14.56
-0.18
A1- AoA
3.80
1.33
1.50*
Val/Met AoA
3.95
1.17
1.57**
Val/Val AoA
0.16
1.54
0.05
Val/Met A1- AoA
-6.41
1.51
-1.91***
Val/Val A1- AoA
-0.73
1.96
Conclusions
Results indicated a three-way interaction such that the relationship between the genetic variants and bilingual proficiency depended on AoA.
At earlier AoAs, having the genetic variant associated with higher levels of subcortical dopamine (A1+) predicted the highest levels of bilingual proficiency.
At later AoAs, individuals with the genetic variant associated with cortical dopamine levels that are balanced between stability and flexibility (Val/Met) predicted the highest levels of bilingual proficiency.
These results fit with theories about the development of language as a subcortical process early in life and as a cortical process later in life 6, as well as the importance of both stability and flexibility in bilingual language development 7.
Finally, this study raises questions about the direction of causality between bilingualism and cognitive control, which is central to the debate over the "bilingual advantage.”
Rather than bilingualism enhancing cognitive flexibility, individuals who are more cognitively flexible may be the ones who go on to develop bilingual proficiency
Cortical Dopamine
Subcortical Dopamine
Val/Val A1-
Low
Val/Val A1+
High
Val/Met A1-
Balanced
Val/Met A1+
Met/Met A1-
Met/Met A1+
Method
Participants: 117 Spanish-English Bilinguals
Age of English acquisition (AOA) measured by a questionnaire
SES measured by questionnaire item about parental education rated from 1(parents have less than an elementary school education) to 6 (parents have graduate degrees)
English and Spanish proficiency measured by Woodcock Language Proficiency Battery-Revised sentence comprehension and vocabulary subtests
Bilingual proficiency calculation:
Significant 3-way interaction between AoA & genotypes to predict bilingual proficiency
References
1Colzato, L. S., Waszak, F., Nieuwenhuis, S., Posthuma, D., & Hommel, B. (2010). The flexible mind is associated with the catechol-O-methyltransferase (COMT) Val158Met polymorphism: evidence for a role of dopamine in the control of task-switching. Neuropsychologia, 48(9), doi: /j.neuropsychologia
2Garcia-Garcia, M., Barcelo, F., Clemente, I. C., & Escera, C. (2011). COMT and ANKK1 gene-gene interaction modulates contextual updating of mental representations. Neuroimage, 56(3), doi: /j.neuroimage
3Stelzel, C., Basten, U., Montag, C., Reuter, M., & Fiebach, C. J. (2010). Frontostriatal involvement in task switching depends on genetic differences in d2 receptor density. Journal of Neuroscience, 30(42), doi: /JNEUROSCI
4Mamiya, P. C., Richards, T. L., Coe, B. P., Eichler, E. E., & Kuhl, P. K. (2016). Brain white matter structure and COMT gene are linked to second-language learning in adults. Proceedings of the National Academy of Sciences,
5Sugiura, L., Ojima, S., Matsuba-Kurita, H., Dan, I., Tsuzuki, D., Katura, T., & Hagiwara, H. (2011). Sound to language: different cortical processing for first and second languages in elementary school children as revealed by a large-scale study using fNIRS. Cerebral Cortex, 21(10), doi: /cercor/bhr023
6Hernandez, A. E., & Li, P. (2007). Age of acquisition: Its neural and computational mechanisms. Psychological Bulletin, 133, doi: /
7Green, D. W., & Abutalebi, J. (2013). Language control in bilinguals: The adaptive control hypothesis. Journal of Cognitive Psychology, 25(5), 515–530. doi: /
Composite proficiency * Balance
Variable
Range
Mean (SD)
AoA
0-17 years
6.54 (3.12)
SES
1 - 6
3.31 (1.43)
English Proficiency
49% - 96%
74.06% (7.41%)
Spanish Proficiency
59% - 88%
76.62% (6.08%)
Bilingual Proficiency
118.66% %
150.10% (10.23%)
Acknowledgments
DNA Samples: 2mL saliva samples collected using DNA Genotek Oragene (OG-500) kits
This research was supported by NIH grant #1R21HD